JP2015514183A - Check valve assembly - Google Patents

Abstract

A check valve assembly (100) for a high pressure fuel injection system is disclosed. A valve chamber (102), wherein the valve (100) is defined in part by a first body portion (106) and in part by a second body portion (108), defining a valve chamber wall (118). And an inlet passage (110) formed in the first body portion (106) that opens into the valve chamber (102) at a valve seat (116) defined by the first body portion (106). A valve chamber engageable with the valve seat (116) to block fluid flow from the outlet passage (112) and the outlet passage (112) to the inlet passage (110) through the valve chamber (102). A valve ball (114) received in (102). The valve chamber wall (118) includes a plurality of guide portions (122a) that guide the valve ball (114) in a substantially linear movement within the valve chamber (102). [Selection] Figure 4

Description

  The present invention relates to a valve assembly for use in a high pressure fuel injection system. In particular, but not exclusively, the present invention relates to a valve assembly for preventing back flow of fuel from a fuel accumulator to a fuel pump.

  FIG. 1 of the accompanying drawings schematically shows a common rail type fuel injection system for use in an internal combustion engine, for example as described in EP-A-1921307. An accumulator volume for fuel, known as common rail 10, receives supply of high pressure fuel from high pressure fuel pump 12. The high pressure pump 12 has a pump chamber 12 a that receives fuel from a low pressure source or reservoir 14 by a metering valve 16. The pump 12 also has a pumping element or plunger 12b that is driven to reciprocate linearly to periodically change the volume of the pump chamber 12a. During the filling or return stroke of the plunger 12b, fuel is withdrawn from the reservoir 14 into the pump chamber 12a, and during the pumping or advancement stroke of the plunger 12b, the fuel is pressurized in the pump chamber 12a and under high pressure the common rail 10 It is pushed in.

  The common rail 10 supplies high pressure fuel to a plurality of fuel injectors 18, only one of which is shown in FIG. Each fuel injector is operable under the control of control valve 20 to inject fuel into the associated cylinder 22 of the engine.

  In order to maintain a high fuel pressure in the common rail 10, especially during the return stroke of the plunger 12 b, and to prevent back flow of high pressure fuel from the common rail 10 toward the pump 12 and metering valve 16, It is necessary to have a check valve 24 (also known as a one-way valve or check valve) in the fuel flow path between the pump 12 and the common rail 10.

  The check valve 24 includes a ball 24a received in the valve chamber 24b. An inlet passage 26 in fluid communication with the pump 12 opens into the valve chamber at the valve seat 24c. The outlet passage 28 is open into the valve chamber at a location remote from the valve seat 24c, and thus fluid communication between the valve chamber 24b and the outlet passage 28 is constantly open. An outlet passage 28 is in fluid communication with the common rail 10.

  The ball 24a is urged toward the valve seat 24c by the valve spring 24d. During the forward stroke of the plunger 12b, the ball 24a moves away from the valve seat 24c, thereby allowing fuel to flow from the inlet passage 26 through the valve chamber 24b and to the common rail 10 through the outlet passage 28. It becomes possible to flow. During the return stroke of the plunger 12b, the ball 24a is engaged with the valve seat 24c by the spring 24d. Thereby, the backflow from the common rail 10 to the pump chamber 12a is prevented. In this configuration, movement of the ball 24a can be accurately controlled by appropriate selection of the spring 24d, which determines the force to bias the ball 24a toward the valve seat 24c.

  It may be desirable to eliminate the valve spring 24d to allow the ball 24c to move freely within the valve chamber 24b to reduce valve component count and increase reliability. There is sex. In such a configuration, during the return stroke of the plunger 12b, the ball 24a is pulled by the partial vacuum obtained by increasing the volume of the pump chamber 12a and engaged with the valve seat 24c, and the valve seat is caused by the high rail pressure acting on the ball 24a. 24c is maintained in contact. Thereby, the backflow from the common rail 10 to the pump chamber 12a is prevented. However, since the force acting on the ball in this configuration is derived only from the fuel pressure acting on each side of the ball 24a, the good controllability of the movement of the ball 24a is reduced, thereby opening and closing the check valve. The predictability of is reduced.

  Under such circumstances, it is desirable to provide a check valve configuration that is highly reliable, has a low number of parts, and accurately defines the opening and closing behavior.

  In a first aspect, the present invention comprises a valve chamber defined in part by a first body portion, partially defined by a second body portion and defining a valve chamber wall, and a first body portion. An inlet passage formed in the first body portion that opens into the valve chamber at a defined valve seat, an outlet passage, and a fluid flow from the outlet passage through the valve chamber to the inlet passage is blocked. A non-return valve assembly for a high pressure fuel injection system comprising a valve ball received in a valve chamber that is engageable with a valve seat. The valve chamber wall includes a plurality of guide portions that guide the valve ball for substantially linear movement within the valve chamber.

  The presence of the guide portion limits the movement of the valve ball so that the position of the valve ball can be predicted more accurately. Thus, advantageously, the present invention makes it possible to optimize the shape of the valve chamber and valve seat to control the opening and closing characteristics of the valve even when the biasing spring is eliminated.

  In addition, by providing a guide portion of the valve chamber wall for guiding the valve ball to move substantially linearly, the position where the ball impacts the valve seat is more accurately controlled than when no guide portion is present. The This allows the ball and valve seat to “be in” relatively early in the valve's operating life (ie, the local region of the valve seat is deformed by plastic flow and / or follows the shape of the ball). To avoid leakage through the valve seat. Similarly, if a lift stop is provided to restrict the ball from moving away from the valve seat, the lift stop will also be “stable” (relatively early in the valve operating life). bed in) ".

  According to one embodiment of the present invention, the first and second body portions can each define a mating surface, wherein a portion of the mating surface of the first body portion is the second body portion. Abuts a portion of the mating surface, thereby forming a seal therebetween. Advantageously, this arrangement is sufficient between the first body portion and the second body portion to prevent leakage from the valve chamber even when the fuel pressure in the valve chamber becomes very high in use. Form a good seal.

  The valve chamber may be formed as a recess in the mating surface of the first body portion. For example, the valve chamber may be formed from a plurality of holes in the mating surface of the first body portion. In one embodiment, the valve chamber is formed from a central hole and a plurality of peripheral holes overlapping the central hole, and the guide portion is preferably defined by a region of the central hole between adjacent peripheral holes. In this case, the valve chamber can comprise a plurality of lobes extending laterally from the central volume. A valve seat may be defined at the inner end of the central hole.

  These configurations allow the valve chamber shape to be accurately defined using a simple manufacturing process. For example, a central hole can be formed by drilling the mating surface of the first body portion, and then the peripheral hole and valve seat can be shaped by a suitable machining process.

  According to one embodiment of the present invention, the mating surface is substantially flat. Providing a flat mating surface helps to ensure a good seal between the surfaces, especially when high flatness is obtained. Thus, the mating surfaces can be ground or otherwise machined.

  The valve assembly may not include a spring. In other words, the valve ball is biased to move so as to be engaged with the valve seat only by the fluid pressure. Alternatively, biasing means such as a spring may be provided to bias the ball to engage the valve seat.

  According to one embodiment of the present invention, the mating surface of the second body portion can define a lift stop for the ball. The lift stop may be a flat surface on the mating surface. Alternatively, the lift stop may be appropriately shaped. If a biasing means is provided, the biasing means can limit the movement of the ball away from the valve seat, in which case a lift stop may not be necessary.

  The outlet passage is preferably formed in the second body portion. In one configuration, the outlet opens on the mating surface of the second body portion. If the valve chamber is formed from a central hole and a plurality of peripheral holes overlapping the central hole, the outlet passage may open into one of the peripheral holes of the valve chamber.

  In order to control the movement of the valve ball, the valve seat may be substantially frustoconical. For example, the valve seat can define a cone angle between about 80 degrees and about 100 degrees, preferably about 90 degrees.

  In one embodiment, the valve chamber wall comprises three guide portions that are equiangularly spaced around the ball. This arrangement has been found to be particularly advantageous both in controlling the movement of the ball and facilitating manufacture. For similar reasons, the guide portion may include a partial cylindrical portion of the valve chamber wall.

  The inlet passage may comprise a partially spherical inlet chamber that opens on the valve seat. In this case, the inlet passage can be inclined with respect to the ball movement axis without adversely affecting the fluid flow at the valve seat. Specifically, by using this configuration, the fluid pressure acting on the ball becomes substantially uniform around the circumference of the valve seat.

  The present invention also includes, in a second aspect, a high pressure fuel pump having a pump chamber, a fuel rail for supplying a plurality of fuel injectors, and a check valve assembly according to the first aspect of the present invention. Range of fuel injection systems for internal combustion engines. Fluid flow from the fuel rail to the pump chamber is blocked by a check valve.

  Preferred and / or optional features according to the first aspect of the invention may be used alone or in appropriate combination in the second aspect of the invention.

  The invention will now be described by way of example only with reference to the remaining accompanying drawings.

FIG. 1 of the accompanying drawings, already referenced above, is a schematic diagram of a known fuel injection system having a check valve located between the pump chamber of the high pressure fuel pump and the fuel rail. 1 is a schematic perspective view showing a first check valve assembly according to the present invention. FIG. It is a schematic longitudinal cross-sectional view which shows the non-return valve assembly of FIG. FIG. 3 is a schematic horizontal sectional view showing the check valve assembly of FIG. 2. FIG. 6 is a schematic perspective view showing a second check valve assembly according to the present invention.

  A check valve assembly 100 according to a first embodiment of the present invention for use in a high pressure fuel injection system is shown in FIGS.

  Referring initially to FIGS. 2 and 3, the valve assembly 100 includes a valve chamber 102 defined within a valve housing 104. The valve housing 104 includes a first housing body portion 106 and a second housing body portion 108. An inlet passage 110 is formed in the first housing body portion 106 for delivering fuel from the pump chamber (not shown) of the associated high pressure fuel pump into the valve chamber 102. An outlet passage 112 is formed in the second housing body portion 108 for conveying fuel from the valve chamber 102 to a high pressure fuel rail (not shown).

  The valve assembly 100 further includes a valve ball 114 that is received within the valve chamber 102. The valve ball 114 is movable in the chamber 102 to engage a valve seat 116 formed in the first housing body portion 106, where the inlet passage 110 is within the valve chamber 102. Open to As shown most clearly in FIG. 3, when the ball 114 is engaged with the valve seat 116, fuel backflow from the valve chamber 102 into the inlet passage 110 is prevented.

  A first housing body portion 106 and a second housing body portion 108 seal each other at respective flat mating surfaces 106a, 108a around the periphery of the valve chamber 102. When the check valve assembly 100 is used in a high pressure fuel injection system, the fuel pressure in the valve chamber 102 may be 200 MPa (2000 bar) or higher. Accordingly, in order to ensure that the seal formed between the abutting mating surfaces 106a, 108a prevents fuel from leaking from the valve chamber 102, the housing body portions 106, 108 are suitable. And firmly clamped together by a clamping means (not shown).

  Advantageously, the check valve assembly 100 can be housed in the housing of a fuel pump (not shown), in which case the fuel pump housing or another component of the fuel pump can form the clamping means. . The valve assembly 100 may instead be housed elsewhere, for example in a separate housing or a common rail housing.

  The valve chamber 102 is formed as a recess in the mating surface 106 a of the first housing body portion 106. As will be described later, the recess is formed from a plurality of overlapping holes extending perpendicular to and inward from the mating surface 106a to define the valve chamber wall 118. Thereby, the valve chamber wall 118 meets the mating surface 106a at a right angle. The end of the recess opposite to the mating surface 106a is closed by the valve chamber roof 120, and the valve seat 116 is formed. The end of the recess at the mating surface 106 a of the first housing body portion 106 is closed by the flat mating surface 108 a of the second housing body portion 108.

  With further reference to FIG. 4, which is a cross-sectional view looking toward the valve chamber roof 120 through the first housing body portion 106, the valve chamber 102 is bounded by three partial cylindrical portions 122 a of the valve chamber wall 118. A central region 122 is provided. In the following, the partial cylindrical portion 122a, known as the guide portion 122a, is located on a common cylinder, so that the central region 122 of the valve chamber 102 forms a generally cylindrical volume.

  Three lobes 124 are disposed equiangularly around the central region 122, with each lobe 124 disposed between two adjacent guide portions 122a. Each lobe 124 is defined by a partial cylindrical portion 124a outside the valve chamber wall 118 and is joined to the central region 122 by a pair of parallel flat wall portions 124b.

  Thus, the valve chamber 102 has, for example, a first central hole that forms a generally cylindrical central region 122 and three separate holes that overlap the central region 122 to define a partial cylindrical wall portion 124a of the lobe 124. And can be formed. The flat wall portion 124b may be formed by suitable machining to combine the partial cylindrical wall portion 124a with each adjacent guide portion 122a. The valve seat 116 may be formed at the inner end of the first hole by suitable machining.

  As shown most clearly in FIG. 4, the three partial cylindrical guide portions 122 a are disposed equiangularly around the valve ball 114. The guide portion 122a is a close clearance fit with respect to the diameter of the valve ball 114, thereby restricting the valve ball 114 from moving sideways by the guide portion 122a. In this way, the movement of the valve ball 114 is moved by the valve chamber wall 118 to an axis (A is attached in FIG. 3) positioned perpendicular to the flat mating surface 108a of the second body portion 108. Guided to a substantially linear movement within the valve chamber 102 along.

  To create a gap or clearance between the guide portion 122a and the ball 114 in order to avoid wear of the ball 114 and to allow the ball 114 to move linearly without interference. In addition, the inner diameter of the cylinder formed by the guide portion 122 a is smaller than the outer diameter of the ball 114. Also, the clearance between the guide portion 122a and the ball 114 allows for any concentric displacement between the valve seat 116 and the guide portion 122a during operation of the valve assembly 100.

  As most clearly shown in FIGS. 2 and 3, the peripheral lobe 124 has a relatively large cross-sectional area for fuel flow through the valve ball 114 when the valve ball 114 is not seated, thereby The presence of the guide portion 122a does not significantly limit the flow rate through the valve.

  As can be seen from FIGS. 2 and 3, a region of the flat mating surface 108 a of the second housing body portion 108 is exposed to the interior of the valve chamber 102. This exposed area defines a lift stop 126 that functions to limit the movement of the valve ball 114 away from the valve seat 116. Since the lateral movement of the ball 114 is limited by the guide portion 122a, the ball 114 always impacts the lift stop 126 at substantially the same position. Thus, advantageously, the repeated impact and deformation of the ball 114 causes the lift stop 126 to “be in” relatively early in the operating life of the valve assembly 100, comparing deformations. Become local.

  The shape of the valve seat 116 can be seen most clearly in FIG. The valve seat 116 includes a frustoconical recess in the valve chamber roof 120. In this example, the cone angle defined by the valve seat 116 is 90 degrees. It has been found that a cone angle of about 90 degrees controls the movement of the ball 114 particularly well. In another embodiment (not shown), the cone angle defined by valve seat 116 may be between about 80 degrees and about 100 degrees.

  In order to withstand high fuel pressures in use, the housing body portions 106, 108 are preferably made from a relatively high strength metallic material, such as high strength steel. The mating surfaces 106a, 108a are preferably precisely ground to have a high level of flatness, thereby helping to ensure a good seal between the surfaces 106a, 108a.

  The inlet passage 110 is in communication with the valve seat 116 via a partially spherical inlet chamber 128 as seen in FIGS. The inlet passage 110 is inclined with respect to the movement axis of the ball 114 (A in FIG. 3). However, the inlet chamber 128 opens on the valve seat 116 at a circular opening coaxial to axis A, so that the fuel pressure is substantially uniform on the ball 114 parallel to axis A. Works.

  Inlet passage 110 leads to inlet chamber 128 at a rounded or smooth transition region 130. By providing a rounded transition region 130 instead of a sharp corner, the associated stress concentration in the first housing body portion 106 is reduced, thereby reducing the risk of fatigue failure. The rounded transition region 130 also helps to improve fluid flow through the inlet passage 110, the inlet chamber 128, and the valve chamber 102.

  Similarly, another rounded transition region 132 of the valve chamber wall 118 is provided where the partial cylindrical portion 124 a and the flat wall portion 124 b of the lobe 124 contact the roof 120 of the valve chamber 102. Again, these rounded transition regions 132 help reduce stress concentrations in the first housing body portion 106 and also help improve fluid flow through the valve chamber 102.

  Similar to the inlet passage 110, the outlet passage 112 is also inclined with respect to the movement axis A of the ball. Outlet passage 112 opens into one of the lobes 124 of valve chamber 102.

  The valve ball 114 is made from a suitable wear-resistant rigid material. For example, the valve ball 114 may be made from a ceramic material such as silicon nitride and may be manufactured by sintering and grinding.

  Next, one embodiment of the use of the valve assembly 100 will be described when the valve assembly 100 of the present invention is used in place of the valve 24 shown in the fuel injection system of FIG.

  In use, the inlet passage 110 is connected to the pump chamber of the high pressure fuel pump and the outlet passage 112 is connected to the common rail. FIGS. 2-4 illustrate the valve assembly 100 with the valve ball 114 in the closed position and engaged with the valve seat 116.

  As the fuel pressure in the inlet passage 110 increases during the pump plunger pumping stroke, the fuel pressure acting on the region of the valve ball 114 upstream of the valve seat 116 and exposed to fuel in the inlet chamber 128 increases significantly. . When the pressure increases in this manner, the bubble ball 114 is pressed away from the valve seat 116, and the valve opens due to the flow of fuel from the inlet passage 110 to the outlet passage 112 through the valve chamber 102. When the ball 114 comes into contact with the lift stop 126, the opening movement of the valve ball 114 is stopped.

  As soon as the ball 114 is disengaged from the valve seat 116, fuel is allowed to flow relatively freely around the ball 114 through the lobe 124 of the valve chamber 102. Thus, the force acting on the ball 114 when moving toward the lift stop 126 is relatively small. Thus, the design of the present invention minimizes damage to the lift stop 126, especially due to the shape of the valve chamber 102 and valve seat 116.

  For example, the selection of the valve seat 116 geometry, particularly the seat width and inner diameter of the seat 116, may be determined to provide the desired opening force for the ball 114. In addition to minimizing damage to the lift stop 126, this optimization of the valve seat geometry thus allows the valve seat 116 where the fuel speed is increased during the initial opening movement of the ball 114. The Bernoulli effect, which acts to reduce the pressure acting on the ball 114, prevents the ball from reciprocating and vibrating within the valve chamber 102, and does not self-close.

  At the start of the return stroke, the pump plunger retracts and the fuel pressure in the inlet passage 110 decreases. A small amount of fuel returns from the valve chamber 102 to the pump chamber, which causes the ball 114 to return and engage the valve seat 116. During the remaining return stroke, the ball 114 is caused to become a valve seat by the pressure in the inlet passage 110 decreasing and the fuel in the outlet passage 112 being relatively high due to the fuel stored in the common rail. 116 is maintained in an engaged state.

  It should be appreciated that the present invention is capable of multiple variations and modifications. For example, FIG. 5 shows a check valve assembly 200 according to a second embodiment of the present invention that differs in the shape of the valve chamber from the valve assembly 100 of FIGS. The remaining features common to both embodiments, appropriately denoted by common reference numerals, are not described in detail.

  In the valve 200 of FIG. 5, the valve chamber 202 has a central region 122 defined by three partial cylindrical guide portions 122a, similar to the first embodiment of the present invention. However, in this second embodiment, the lobes 124, 224 of the valve chamber 202 have different dimensions.

  One lobe 124 with the outlet passage 112 open is defined by a partial cylindrical portion 124a outside the valve chamber wall 118 and joined to the central region 122 by a pair of parallel flat wall portions 124b.

  The remaining two lobes 224 (only one is shown in FIG. 5) are defined only by the partial cylindrical portion 224a of the valve chamber wall 118, and no flat wall portion is used. In other words, the partial cylindrical portion 224a is directly connected to the guide portion 122a. Thus, the cross section of these two lobes 224 is smaller than the lobe 124 where the outlet passage 122 is open.

  The invention is capable of further variations and modifications. Specifically, the geometry of the valve chamber, valve seat, inlet chamber, and inlet and outlet passages can be modified to optimize the valve performance for a given application. In this regard, modeling the valve geometry during design and optimization is greatly simplified compared to configurations where the valve ball can move freely laterally as well as axially. For this reason, it is advantageous for the valve ball to be guided along a substantially linear movement axis.

  In the illustrated embodiment, the lift stop 126 is initially a flat surface, but it should be appreciated that the lift stop 126 may be somewhat deformed when the valve ball is bedped in. However, in other embodiments, a molded or contoured lift stop may be provided.

  The configuration of three guide portions and three lobes as shown in the illustrated embodiment is relatively easy to manufacture. However, it should be appreciated that more or fewer than three guide portions and lobes may be provided instead.

  The illustrated embodiment of the present invention does not require a biasing spring to bias the valve ball into engagement with the seat. In such a springless configuration, the valve ball is moved to engage the seat only by fluid pressure. However, in other configurations, a spring biasing means or another elastic biasing means may be provided, in which case the flat mating surface of the second body portion is not as a lift stop but for the spring. It can be used as an abutment surface.

  Other modifications and variations of the present invention may be contemplated without departing from the scope of the present invention as defined in the appended claims.

Claims (13)

A check valve assembly (100) for a high pressure fuel injection system comprising:
A valve chamber (102) defined in part by a first body portion (106), partially defined by a second body portion (108) and defining a valve chamber wall (118), said first One body portion (106) and the second body portion (108) each define a substantially flat mating surface (106a, 108a), and the pair of first body portions (106). A portion of the mating surface (106a) abuts a portion of the mating surface (108a) of the second body portion (108), whereby the first body portion (106) and the second body portion ( A valve chamber (102) in which a seal is formed between
An inlet passage (110) formed in the first body portion (106) that opens into the valve chamber (102) at a valve seat (116) defined by the first body portion (106); ,
An exit passageway (112);
In the valve chamber (102), engageable with the valve seat (116) to block fluid flow from the outlet passage (112) to the inlet passage (110) through the valve chamber (102). A valve ball (114) received in the
The valve chamber wall (118) comprises a plurality of guide portions (122a) for guiding the valve ball (114) to move substantially linearly within the valve chamber (102).
Check valve assembly (100).   The check valve assembly of claim 1, wherein the valve chamber (102) is formed as a recess in the mating surface (106a) of the first body portion (106).   The check valve assembly of claim 2, wherein the valve chamber (102) is formed from a plurality of holes in the mating surface (106a) of the first body portion (106).   The valve chamber is formed from a central hole and a plurality of peripheral holes overlapping the central hole, and the guide portion (122a) is defined by a region of the central hole between adjacent peripheral holes. Item 4. The check valve assembly according to item 3.   The check valve assembly of claim 4, wherein the valve seat (116) is defined at an inner end of the central bore.   Check valve assembly according to any one of the preceding claims, wherein the mating surface (108a) of the second body portion (108) defines a lift stop (126) for the ball. Solid.   The check valve assembly according to any of the preceding claims, wherein the outlet passage (112) is formed in the second body portion (108).   A check valve assembly according to any one of the preceding claims, wherein the valve seat (116) is substantially frustoconical.   The check valve assembly of claim 8, wherein the valve seat (116) defines a cone angle between about 80 degrees and about 100 degrees, preferably about 90 degrees.   Check valve assembly according to any one of the preceding claims, wherein the valve chamber wall (118) comprises three guide portions (122a) spaced equiangularly around the ball (114). Solid.   The check valve assembly according to any one of the preceding claims, wherein the guide portion (122a) comprises a partial cylindrical portion of the valve chamber wall (118).   The check valve assembly according to any one of the preceding claims, wherein the inlet passage (110) comprises a partially spherical inlet chamber (128) opening on the valve seat (116). A fuel injection system for an internal combustion engine comprising:
A high pressure fuel pump having a pump chamber;
A fuel rail for supply to a plurality of fuel injectors;
A check valve assembly (100) according to any one of the preceding claims,
Fluid flow from the fuel rail to the pump chamber is blocked by the check valve assembly (100);
Fuel injection system.

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